The present invention relates to adhesive and/or sealant compositions, to novel compounds which may be used in the compositions and to methods of their production.
The applicants have found that certain unsaturated monomeric compounds can, under particular conditions, polymerise so as to form effective adhesion between surfaces.
According to the present invention there is provided an adhesive or sealant composition comprising a compound of formula (I) 
where
R1 is CH and R6 is a bond, or R1 and R6 together form an electron withdrawing group;
R2 and R3 are independently selected from (CR8xe2x80x2R8)n, or a group CR9R10, xe2x80x94(CR8xe2x80x2R6CR9R10)xe2x80x94 or xe2x80x94(CR9R10CR8xe2x80x2R8)xe2x80x94 where n is 0, 1 or 2, R8xe2x80x2 and R8 are independently selected from hydrogen or alkyl, and either one of R9 or R10 is hydrogen and the other is an electron withdrawing group, or R9 and R10 together form an electron withdrawing group,
R4 and R5 are independently selected from CH or CR11 where R11 is an electron withdrawing group, and
R7 is hydrogen, an optionally substituted hydrocarbyl group, a perhaloalkyl group or a functional group;
the dotted lines indicate the presence or absence of a bond,
and X1 is a group CX2X3 where the dotted line bond to which it is attached is absent and a group CX2 where the dotted line bond to which it is attached is present, Y1 is a group CY2Y3 where the dotted line bond to which it is attached is absent and a group CY2 where the dotted line bond to which it is attached is present, and X2, X3, Y2 and Y3 are independently selected from hydrogen and fluorine;
provided that at least one of (a) R1 and R6 or (b) R2 and R3 or (c) R4 and R5 includes an electron withdrawing group;
and where necessary, a polymerization initiator.
As used herein, the expression xe2x80x9cadhesive or sealant compositionxe2x80x9d includes either an adhesive composition and/or a sealant composition. An xe2x80x9cadhesive compositionxe2x80x9d is a gluexe2x80x94like material which, when interposed between surfaces, will hold the surfaces together. The resulting bond between the surface is sufficiently strong and will remain in place for a period of time which is appropriate for the desired application. Surfaces include glass, metal, wood, paper, card, ceramics, plastics, laminates, stone, construction materials as well as biological material such as tissue. The expression xe2x80x9csealant compositionxe2x80x9d refers to compositions which may be applied to one or more surfaces to form a protective barrier thereon, for example to prevent ingress or egress of solid, liquid or gaseous material or alternatively to allow selective permeability through the barrier to gas and/or liquid. In particular, it may provide a seal between surfaces.
Preferably, where R2 and R3 are both (CR7R8)n, at least one n is 1 or 2. Suitably in formula (I), n is 1 or 2.
As used herein, the term xe2x80x9calkylxe2x80x9d refers to straight or branched chain alkyl groups, suitably containing up to 20 and preferably up to 6 carbon atoms. The term xe2x80x9calkenylxe2x80x9d and xe2x80x9calkynylxe2x80x9d refer to unsaturated straight or branched chains which include for example from 2-20 carbon atoms, for example from 2 to 6 carbon atoms. Chains may include one or more double or triple bonds respectively. In addition, the term xe2x80x9carylxe2x80x9d refers to aromatic groups such as phenyl or naphthyl.
The term xe2x80x9chydrocarbylxe2x80x9d refers to any structure comprising carbon and hydrogen atoms. For example, these may be alkyl, alkenyl, alkynyl, aryl such as phenyl or napthyl, aralkyl, cycloalkyl, cycloalkenyl or cycloalkynyl. Suitably they will contain up to 20 and preferably up to 10 carbon atoms. The term xe2x80x9cheterocyclylxe2x80x9d includes aromatic or non-aromatic rings, for example containing from 4 to 20, suitably from 5 to 10 ring atoms, at least one of which is a heteroatom such as oxygen, sulphur or nitrogen. Examples of such groups include furyl, thienyl, pyrrolyl, pyrrolidinyl, imidazolyl, triazolyl, thiazolyl, tetrazolyl, oxazolyl, isoxazolyl, pyrazolyl, pyridyl, pyrimidinyl, pyrazinyl, pyridazinyl, triazinyl, quinolinyl, iosquinolinyl, quinoxalinyl, benzthiazolyl, benzoxazolyl, benzothienyl or benzofuryl.
The term xe2x80x9cfunctional groupxe2x80x9d refers to reactive groups such as halo, cyano, nitro, oxo, C(O)nRa, ORa, S(O)tRa, NRbRc, OC(O)NRbRc, C(O)NRbRc, OC(O)NRbRc, xe2x80x94NR7C(O)nR6, xe2x80x94NRaCONRbRc, NRaCSNRbRc, xe2x80x94Cxe2x95x90NORa, xe2x80x94Nxe2x95x90CRbRc, S(O)tNRbRc, C(S)nRa, C(S)ORa, C(S)NRbRc or xe2x80x94NRbS(O)tRa where Ra, Rb and Rc are independently selected from hydrogen or optionally substituted hydrocarbyl, or Rb and Rc together form an optionally substituted ring which optionally contains further heteroatoms such as S(O)t, oxygen and nitrogen, n is an integer of 1 or 2, t is 0 or an integer of 1-3. In particular the functional groups are groups such as halo, cyano, nitro, oxo, C(O)nRa, ORa, S(O)tRa, NRbRc, OC(O)NRbRc, C(O)NRbRc, OC(O)NRbRc, xe2x80x94NR7C(O)nR6, xe2x80x94NRaCONRbRc, xe2x80x94Cxe2x95x90NORa, xe2x80x94Nxe2x95x90CRbRc, S(O)tNRbRc, or xe2x80x94NRbS(O)tRa where Ra, Rb and Rc, n and t are as defined above.
The term xe2x80x9cheteroatomxe2x80x9d as used herein refers to non-carbon atoms such as oxygen, nitrogen or sulphur atoms. Where the nitrogen atoms are present, they will generally be present as part of an amino residue so that they will be substituted for example by hydrogen or alkyl.
A particular functional group for R7 is an amide. The term xe2x80x9camidexe2x80x9d is generally understood to refer to a group of formula C(O)NRaRb where Ra and Rb are hydrogen or an optionally substituted hydrocarbyl group.
Suitable *polymerization initiators for inclusion in the compositions of the invention will depend upon the nature of the compound of formula (I) and the intended use to which the adhesive or sealant is to be put. For instance, where an adhesive is intended for use in circumstances where it is or may be exposed to ultraviolet radiation, such as in the adhesion of transparent materials such as glass, the compound of formula (I) is suitably a compound which will polymerise or cure under the influence of u.v. radiation. In such cases, suitable polymerisations initiators will include 2,2xe2x80x2-azobisisobutyronitrile (AIBN) aromatic ketones such as benzophenones in particular acetophenone; chlorinated acetophenones such as di- or tri-chloroacetophenone; dialkoxyacetophenones such as dimethoxyacetophenones (sold under the Trade name xe2x80x9cIrgacure 651xe2x80x9d); dialkylhydroxyacetophenones such as dimethylhydroxyacetophenone (sold under the Trade name xe2x80x9cDarocure 1173xe2x80x9d); substituted dialkylhydroxyacetophenone alkyl ethers such compounds of formula 
where Ry is alkyl and in particular 2,2-dimethylethyl, Rx is hydroxy or halogen such as chloro, and RP and Rq are independently selected from alkyl or halogen such as chloro (examples of which are sold under the Trade names xe2x80x9cDarocure 1116xe2x80x9d and xe2x80x9cTrigonal P1xe2x80x9d); 1-benzoylcyclohexanol-2 (sold under the Trade name xe2x80x9cIrgacure 184xe2x80x9d); benzoin or derivatives such as benzoin acetate, benzoin alkyl ethers in particular benzoin butyl ether, dialkoxybenzoins such as dimethoxybenzoin or deoxybenzoin; dibenzyl ketone; acyloxime esters such as methyl or ethyl esters of acyloxime (sold under the trade name xe2x80x9cQuantaqure PDOxe2x80x9d); acylphosphine oxides, acylphosphonates such as dialkylacylphosphonate, ketosulphides for example of formula 
where Rz is alkyl and Ar is an aryl group; dibenzoyl disulphides such as 4,4xe2x80x2-dialkylbenzoyldisulphide; diphenyldithiocarbonate; benzophenone; 4,4xe2x80x2-bis(N,N-dialkylamino)benzophenone; fluorenone; thioxanthone; benzil; or a compound of formula 
where Ar is an aryl group such as phenyl and Rz is alkyl such as methyl (sold under the trade name xe2x80x9cSpeedcure BMDSxe2x80x9d).
Such compositions may be used in applications where it is possible to deliver uv radiation, for example by means of a fibre optic conductor, so as to cause the adhesive or sealant to cure.
Other conventional polymerization initiators including free radical initiators, as are known in the art can be employed.
In another embodiment, the compound of formula (I) is one which will polymerise following initiation by exposure to an electron beam as is understood in the art.
Thermally curable adhesive or sealant compounds of formula (I) can be produced and used in circumstances where heating to the desired temperature is possible, for example in the production of laminates.
The nature of the electron withdrawing group or groups in the compound of formula (I) will depend upon its position in relation to the double bond it is required to activate, as well as the nature of any other functional groups within the compound.
Initiators, where required, will be present in an amount which is sufficient to induce the required reaction in an appropriate time period. Typically, the composition will comprise from 1-10% w/w initiator, suitably about 4-6% w/w initiator depending upon the nature of the compound of formula (I), the type of initiator used, the intended function etc.
In a particular embodiment, the dotted bonds shown in Formula (I) are absent. Thus, certain compounds of formula (I) can be represented as formula (IA) 
(IA)
where R1, R2, R3, R4, R5, R6, R7, X2, X3, Y2 and Y3 are as defined above in relation to formula (I).
In a preferred embodiment, R1 and R6 form an electron withdrawing group. In this case, it is preferred that R2 and R3 are groups (CR8xe2x80x2R8)n and R4 and R5 are CH groups.
For example, R1 is a heteroatom or a substituted heteroatom which has electron withdrawing properties, for example a group N+R12 (Zmxe2x88x92)1/m, S(O)pR13, B, P(O)qR14 or Si(R15) where R12, R13, R14 and R15 are independently selected from hydrogen or hydrocarbyl, Z is a anion of valency m, p is 0, 1 or 2, and q is 0, 1, 2 or 3; and R6 is a bond.
Suitably hydrocarbyl groups for R12, R13, R14 and R15 include alkyl and alkenyl groups.
The nature of the anion Z, where present, will affect the properties of the final adhesive or sealant and in particular, its conductivity. Suitable anions for the Z group include halide ions such as fluoride, chloride, bromide or iodide, borides such as boron tetrafluoride; carboxylic acid esters such as those of formula R14C(O)Oxe2x88x92 where R14 is an optionally substituted hydrocarbyl group group such as haloalkyl, in particular trifluoromethyl; and other anionic groups such as mesylate and tosylate. In general, the water permeability of the ultimate polymer will vary as follows:
PF6xe2x88x92 less than BF4xe2x88x92 less than CF3SO3xe2x88x92 less than CF3COOxe2x88x92 less than NO3xe2x88x92 less than SO42xe2x88x92 less than Ixe2x88x92 less than Br31  less than Clxe2x88x92
Other factors which affect water permeability of the adhesive or sealant is the nature of any group to which the group of sub-formula (I) is attached. When this contains for example perhaloalkyl substituents such as perfluoroalkyl, it will be largely water impermeable as compared to adhesives or sealants which have alkylene bridging groups optionally interposed with say oxygen.
High water permeability provides the advantage that any excess adhesive or sealant applied can be easily removed using water.
Alternatively, R1 is a group CH and R6 is a group xe2x80x94C(O)Oxe2x80x94 or xe2x80x94OC(O)xe2x80x94 or xe2x80x94S(O)2xe2x80x94. Suitably R6 is a group xe2x80x94C(O)Oxe2x80x94 or xe2x80x94OC(O)xe2x80x94.
Most preferably, the combination of R1 and R6 forms an amide group, where R1 is a nitrogen atom and R6 is a carbonyl group. Alternatively the combination forms a sulphonamide group where R1 is a nitrogen atom and R6 is a sulphonyl group. The nitrogen atom of the amide group may or may not form part of a group N+R12(Zmxe2x88x92)1/m as described above, depending upon the nature of the compound of formula (I) and the nature of any initiator used in the composition. In other words, the nitrogen may be quaternised or may not since the electron withdrawing effect of the group R6 in this case will produce the necessary level of activation of the double bond.
Alternatively, where the activation is effected by electron withdrawing groups at a position indicated by R2 or R3, suitable electron withdrawing groups R9 and R10 include carbonyl, nitrile, trifluoromethyl, acyl or nitro, preferably R9 and R10 together form an oxo group.
Where R11 is an electron withdrawing group, it is suitably acyl, nitrile or nitro.
Preferably X2, X3, Y2 and Y3 are all hydrogen or all fluorine and in particular they are all hydrogen.
A preferred group of the compounds for use in the method of the invention is a compound of structure (II) 
where R7 is as defined in relation to formula (I) and xe2x80x94R19xe2x80x94 is C(O), C(S) or S(O)2. Preferably R19 is a group xe2x80x94C(O)xe2x80x94.
A furthers preferred group of compounds for use in the method of the invention are compounds of compounds of formula (IIA) 
where R7 is as defined in relation to formula (I).
Preferably R7 is an optionally substituted hydrocarbyl group, a perhaloalkyl group or an amide.
Suitable optional substituents for hydrocarbyl groups R7 in the compound of formula (I) include functional groups as defined above, such as cyano. Preferably, R7 includes an unsaturated moiety, in particular any aryl or alkenyl group, or a substituent which involves a double bond such as is found in a carbonyl group.
In particular R7 is an optionally substituted alkyl, alkenyl, alkynyl or aryl group.
Preferred substituents for R7 include carboxy or salts or esters thereof and acyloxy. Suitable salts for carboxy groups are metal salts, in particular alkali metal salts such as lithium, sodium or potassium, alkaline earth metal salts such as magnesium or calcium salts or organic salts such as quaternary ammonium salts. Suitable quaternary ammonium salts contain optionally substituted hydrocarbyl groups. In particular, they comprise alkyl groups substituted by hydroxy or interposed with oxygen atoms. Multiple salts containing more than one molecule of formula (I) may be formed where the cation has a valency of greater than one. In particular, hydrocarbyl group having more than one quaternary ammonium substituent will have the effect of associating molecules of formula (I) together as illustrated hereinafter.
Suitable ester groups include optionally substituted hydrocarbyl esters such as optionally substituted alkyl, of aryl esters, where the optional substituents include for example functional groups such as halo.
Where R7 is a perhaloalkyl group, it is suitably comprises from 1 to 3 carbon atoms, such as perfluoromethyl.
Suitable amide groups R7 are hydrocarbyl amides or hydrocarbyl sulphonamides, and in particular include dialkenyl substituted amides such as those of sub formula (III) 
where R19 is as defined above in relation to formula (II) R12 and R13 are selected from groups defined above for R2 and R3 in relation to formula (I) and R14 and R15 are selected from groups defined above as R3 and R4 in relation to formula (I). In particular, R12 and R13 are xe2x80x94CH2xe2x80x94 or xe2x80x94CH2CH2xe2x80x94 groups and R14 and R15 are xe2x80x94CHxe2x80x94 groups. The amide groups may themselves become involved in the polymerization process, thus allowing branched or network polymers to be formed as the adhesive or sealant is cured.
Suitably R19 is a group C(O).
Particular examples of compounds of formula (II) are listed in Table 1
A further sub-group of the compounds of formula (I) are compounds of formula (IV) 
where X1, Y1, Z, m and the dotted lines are as defined above, the hydrogen atoms in bracket are absent when the dotted lines represent the presence of a bond, R16 and R17 are independently selected from hydrogen and hydrocarbyl which may be optionally substituted by hydroxy, in particular alkyl and alkenyl such as prop-2-enyl or a hydroxyalkyl such as hydroxyethyl or a group of formula xe2x80x94C((CH2)dOH)a(H)b where a is an integer of from 1 to 3 and b is 0 or an integer of 1 or 2 provided that a+b is 3, and d is an integer of from 1 to 6, preferably 2 or 3.
The presence of hydroxy groups as substitutents R16 and R17 groups may be preferred in that these groups can make the compounds of formula (IV) water soluble, allowing for the possibility that water based adhesives or sealants can be produced.
Particular examples of compounds of formula IV include compounds of formula (IVA) 
where R16, R17 Z and m are as defined in relation to formula (IV) and some are listed in Table 2.
Other compounds of formula (I) include those listed in Table 3.
Certain compounds of formula (I) are novel and these form a further aspect of the invention.
In particular, there is provided a compound of formula 
where R2, R3, R4, R5, X1 and Y1 and the dotted lines are as defined in relation to formula (I) and R18 is R7 as defined in relation to formula (I) provided that where R2 and R3 are both CH2 and R4 and R5 are both CH, R18 is other than methyl, chloromethyl or trichloromethyl.
Preferably, R18 is other than alkyl or haloalkyl including perhaloalkyl.
In particular, the compound of formula (V) is a compound of formula (VA) 
where R2, R3, R4, R5 and R12 is as defined in relation to formula (V).
Novel compounds of formula (IV) above include those where R16 and/or R17 are alkenyl or alkynyl groups and these form a further aspect of the invention.
Adhesive or sealant compositions of the invention may include additional reagents such as solvents, plasticisers, curing agents, dyes, fillers etc as is understood in the art. Preferably, as discussed above, the compositions include water as a solvent. However, where the compound of formula (I) has a relatively high viscosity, an organic solvent such as dichloromethane, acetone, tetrahydrofuran etc. may be present in order to ensure that the composition is homogenous and will spread well. Suitably, any solvent will be present in an amount of from 200 to 300% w/w.
Compounds of formula (I) may be prepared by conventional methods. For example, they may be prepared by reacting a compound of formula (VI) 
where R1, R2, R31, R4, R5, X1, Y1 and the dotted lines are as defined in relation to formula (I), and R20 is hydrogen or hydroxy, with a compound of formula (VII)
R7xe2x80x94R6xe2x80x94Z1xe2x80x83xe2x80x83(VII)
where R6 and R7 are as defined in relation to formula (I) and Z1 is a leaving group.
Suitable leaving groups Z1 include halogen in particular bromo, mesylate or tosylate. The reaction is suitably effected in an organic solvent such as tetrahydrofuran, dichloromethane, toluene, alcohols such as ethanol, methanol, or ketones such as butanone and elevated temperatures in the region of the boiling point of the solvent.
Preferably the reaction is effected in the presence of a base such as potassium carbonate.
Compounds of formulae (VI) and (VII) are either known compounds or they can be prepared from known compounds by conventional methods.
Adhesives in accordance with the invention can be used in a variety of applications depending upon the precise nature of the compounds of formula (I). For example, they may be used to form bonds between glass surfaces, surfaces between metals and glass and in the production of laminates and shatter-proof glass. By forming the compound of formula (I) so that it includes a charged group, the adhesives may provide an electrically conducting layer.
Adhesives of the invention may also have applications in biomedical fields. For example, biocompatible compounds of formula (I) may be used to adhere molds or splints in place, or to adhere tissues, or in the formation of internal welds. Biocompatible compounds preferably include amide groups as the electron withdrawing groups as these most closely resemble naturally occurring amino acids.
Thus the invention further provides a method of adhering surfaces to one another, said method comprising applying to at least one surface, a compound of formula (I) as described above, contacting said treated surface with the surface to which it is to be adhered, and allowing the compound of formula (I) to polymerise.